Dental drilling and apparatus therefor



April 2, 1963 B. BROOKS ETAL 3,083,463

DENTAL DRILLING AND APPARATUS THEREFOR Filed April 15, 1961 INVENTORS BERNARD BROOKS ALLE N A. SYLVANE Mil 014 A TORNEYS .portant disadvantages inherent in both of these.

.joyed very little public acceptance.

United States Patent 3,083,463 DENTAL DRILLING AND APPARATUS THEREFQR Bernard Brooks and Allen A. Sylvanc, Rockaway Beach, NY. Filed Apr. 13, 1961, Ser. No. 1.925% 9 Claims. (Cl. 3248) This invention relates to an improvement in dental drilling techniques, and more particularly to a method and apparatus for relieving pain from drilling by a form of electric anesthesia which is administered through the drilling bur directly at its point of contact with the tooth, current being generated in the drilling bur by its rotation in a magnetic field passed through the affected area of the patients mouth. The present application is a continuation-in-part of our application Serial No. 780,876 filed December 16, 1958, entitled Dental Drilling and now abandoned.

The need to relieve pain from dental drilling has prompted many improvements in the field of dental anesthesia. The two general types of anesthetics most widely used today are the local or novocaine type and the "general or nitrous oxide type. There are several im In the local type, novocaine deadens an unnecessarily large area of the mouth. It also takes a considerable amount of time before its effect is felt, and then it lingers long after it is required, subjecting the patient to resulting discomfort. The 'gas or general anesthetic is limited primarily by its undesirable side effects. It frequently causes nausea and extreme dizziness. In the case of certain cardiac patients it is necessarily prohibited.

Electric anesthesis, though introduced early, has en- Prior to our invention, the most advanced techniques used an externally generated direct current, applied directly to the tooth by the drill bur as the positive electrode, which flows to a negative electrode that must be attached at some other point to the patients body. In using this technique extreme care must be exercised to prevent harmful shocks and to avoid the possibility of sending the patient into convulsions. These dangers along with the necessity for the unpleasant negative electrode attachment to the patients body have made this form of anesthetic technique unattractve to the patent as well as to the dental profession.

All of the above listed techniques have additional cornmon disadvantages which are substantially reduced in our invention. In all of them the equipment is complex and expensive. It also requires extremely close control to avoid harm to the patient, especially in the case of gas and electric anesthesia. In addition, there is the patients psychological repugnance to the administering of the anesthetic by any of the means employed, whether by the hypodermic needle, face mask, or electrical lead.

As an answer to these problems our invention is a simple device which effectively and safely anesthetizes the patient with the minimal discomfort and the least incon venience to the dentist. In its simplest form our technique calls for performing the drilling operation so that the bur rotates in a magnetic field which is placed across the affected area of the tooth. No external current and no electrode attachments running to the patients body are required. Current is generated in the bur by its rotation in the magnetic field, and the current works directly 3,083,463 Patented Apr. 2, 1953 on the nervous system of the affected tooth without involving the circulatory or respiratory systems of the body. The anesthetic effect is limited to the specific area involved and only for such a duration of time as that area is in pain.

The control of the apparatus is simple and safe. Anesthetic effect can be varied by adjusting the magnetic field intensity, as by changing either the current or the number of turns in an electromagnetic coil serving to produce the field. In this manner the anesthetic effect can be easily and precisely adjusted to suit each patients particular needs for each step of the drilling operation.

Experiments have verified the effectiveness of this control arrangement and have also demonstrated two additional means for providing an improved anesthetic effect. One is the use of a drilling bur embedded with an insulated coil of fine wire, one of the leads of the coil being connected to the bur tip and the other connected to the bur shank. Another is the circulation of salt water around the affected area of the patients tooth and gums during the drilling operation. These two variations in our new method can be used either independently or conjointly with the applied magnetic field. They Will be more fully explained in the detailed description of our apparatus which follows.

The principal object of this invention is thus to provide a dental drilling method and apparatus with a simple and inexpensive built-in anesthetic capability.

It is another object of this invention to produce an anesthesia localized only to the specific area of pain and lasting only as long as actually required, avoiding unnecessary and lingering discomfort to the patient.

' It is a further object of this invention to produce an anesthesia with no harmful or distasteful side effects to the patient.

It is a still further object of this invention to provide a safe and easily adjustable anesthetic device readily adaptable to each patients particular needs.

Other objects and features of the invention will. be apparent when the following detailed description is considered in connection with the annexed drawing, in which:

FIGURE 1 is a perspective view of the patients upper jaw with two electromagnet poles in position outside the jaw, and a dental handpiece and bur engaged for drilling the patients tooth;

FIGURE 2 is a cross-sectional view of a tooth being worked on, showing the dental handpiece and bur contacting the tooth with the electromagnetic poles positioned so as to pass the magnetic field across the crown of the tooth and normal to the rotational axis of the bur;

FIGURE 3 is an elevational view of one form of the dental bur of FIGS. 1 and 2, modified according to our invention; and

FIGURE 4 is a fragmentary vertical cross-sectional view of the dental bur of FIGURE 3. I

Referring now to the drawings and particularly to FIGURES 1 and 2 which illustrate a typical application of our invention, the dental handpiece 4 is connected by pivoted linkages to the dental unit which usually includes a chair, cuspidor and electric motor drive. It is unnecessary to show these latter elements since they are generally standard pieces, and they are not truly pertinent to this invention. Power is transmitted from the motor by a conventional belt and pulley transmission .to a drill shaft in the dental handpiece 4. A drill bur 5 is driven by the drill shaft, completing the transmission of rotational power from the motor.

The drill bur comes in various sizes and configurations, suited to the particular type of operation involved. Bur characteristics are important to our invention primarily in that the bur is made of steel, it rotates at a high rate of speed when in operation usually between 6000 and 25,000 -r.p.m., but up to 250,000 rpm. in modern equipment, and the bur shank in a preferred form of the invention, has suificient body to permit winding or embedding a .coil in it without seriously impairing its torque strength (FIG. 4). The average shank is shaped like a shaft and measures approximately %2" in diameter and /2" in length. The importance of these characteristics will become apparent from the following description.

The two magnetic pole pieces 2 and 3 are of constant, opposite polarity, that is with a north pole on one side of the jaw and a south pole on the other. The poles may illustratively be produced by a single electromagnet in the shape of a yoke that fits loosely around the patients head and jaws. Alternatively, the poles may be produced by two separate electromagnets mounted about the head with opposite poles directed toward each side of the patients jaws.

ment.

The electromagnets just described are illustrative only. The magnet may be of a permanent type, and it may also be suitably formed to permit positioning inside the mouth if desired. For example, dental probe mirrors may have small permanent magnets attached at the mirror end. This permits more direct positioning of the magnet at the proper angle across the afiected tooth during the drilling. It also provides a more versatile and less cumbersome magnetic field source, although the magnetic field intensity usable is not so large as with external magnets.

Electromagnets are normally preferable to permanent magnets, because their produced fields can be easily varied. The importnace of this case of variability is that it provides an excellent system for an adjustable control of the anesthesia, as will be discussed in the following paragraphs. The field strength produced by permanent magnets can be varied for purposes of this invention only by the inconvenient method adding or removing magnets or by adjustable shunts. On the other hand, the field of an electrom'agnet can be varied by simply adjusting the current going through the turns around the core. The variable direct current necessary for these adjustable electromagnets can be supplied by any of the methods known in the electrical industry, such as rectifying the standard 110 or 220 volts, 60 cycle current by a suitable thermionic tube circuit and then passing it through a calibrated rheostat for precise amperage control.

To produce the anesthetic effect, the drilling bur and the magnetic field must be used in conjunction with each other. The magnetic poles 2 and 3 should be positioned so as to concentrate the magnetic field across the crown of the tooth 1. The poles 2 and 3 should also be positioned as shown in FIGURE 2, so that the axis of the field (line connecting the poles) will be at an angle to the rotational axis of the drill bur 5, preferably approaching a right angle so as to maximize the burs flux cutting ability. With the magnetic poles suitably positioned, the drilling is then commenced, and the burs rotation in the magnetic field generates the necessary voltage for the electric anesthesia.

Referring to FIGURES 3 and 4, a significant feature of 4 this invention is a special configuration at the drill bur 5 which vastly improves the capabilities of this anesthetic technique. By embedding an additional conductor in the bur shank, such as a coil of insulated wire 6, the bur 5 can generate higher currents in lower strength fields for more effective anesthetic action on the dentinal nerves.

By way of example, a coil 6 may be embedded in a bur for this purpose by first drilling small holes across the bur 5 at each end of the shank. Recesses on opposite sides of the shank may then be grooved longitudinally between the holes, leaving sufiicient metal on the centerline of the bur to maintain its torque strength and also to serve as a winding core for the coil. A length of fine insulated copper wire is then threaded and coiled through the holes and around the remaining core of the bur. One end of the coil is connected to the bur shank 7. The other end may be connected directly to the tip, or as illustrated, it is run through a fine bore in the center of the bur tip 8. Insulation is then removed from the exposed point of the coil to provide direct point contact between the coil terminal and the tooth. Such a bur has produced very satisfactory results.

Alternative methods for fabricating this coil into the bur may also be used. For example, printed circuit techniques might be used. Conductors in shapes other than coils may be used to accomplish this same purpose. The method of manufacture and shape of conductor are not critical. The important'feature is that the additional conductor is so shaped and so placed-to maximize the burs flux cutting ability.

It is also clear that a graduated set of coiled burs could be fabricated to cover a broad range of anesthetizing requirements, leaving the fine adjustment to an adjustment of the field intensity as discussed above. For example, for a particular type of bur there might be separate ten-turn, twenty-turn and thirty-turn coil models which in turn would produce broad range variations of anesthetic effect.

We have also discovered that the anesthetic efiect can be considerably improved by bathing the gum area adjacent to the affected tooth in a saline solution during the drilling operation. A solution having a concentration of 5 ppm. is suitable. The salines efiect is not clearly understood, but it apparently acts as an electrolytic conductor for freer flow of current to the dental nerves. It may also affect the magnetic permeability in the vicinity of the afiected tooth so as to improve the anesthetic effect. Whatever the reason, it was proved experimentally to be effective. Other less distasteful electrolytes may be substituted for the saline solution.

For a more specific description of a typical operation employing variable-strength electro-magnet-s and coiled drill burs, the patient is first seated in the dental chair with his head held steady in the headrest. The dentist then positions the opposite poles of the electromagnets 2 and 3 to concentrate the magnetic field across the top of the tooth 1 at an angle to the intended axis of rotation of the drill bur (FIGURES 1 and 2) estimated to yield the maximum flux cutting. The dentist then energizes the electromagnet at a level preselected for the particular operation, lower field strength being required if the operation calls for a slight grinding treatment rather than a more painful penetrating drilling. The dentist similarly selects and connects the proper drill bur 5 with the suitable additional conductor 6 and then commences drilling. The field strength may then be adjusted either manually or by a remote foot pedal as required to minimize the pain throughout the operation.

We recognize the fact that the exact neurological effects of this technique are not fully understood. Apparently the rotating bur 5 and additional conductor 6 generate a minute alternating current which flows into the dentinal nerves, producing the anesthetic efiect. Regardless of the theory, its beneficial eifects have been empirically established. Illustrative data obtained in actual use are here listed to facilitate a fuller and more useful understanding of our invention. Values listed are not critical, but rather are representative of broad ranges. This is necessarily so since anesthesia is essentially a subjective phenomenon. This subjectivity emphasizes the desirability of the adjustable version of our invention.

Conditions Drill speed-varying between 6,000 and 20,000 rpm.

Magnetic fieldbetween 800 and 1,000 gauss in the air gap at point of drilling.

Imbedded coil-approximately six inches of insulated 32 A.W.G. copper wire coiled in the bur as described above.

Saline solution-approximate strength 5 p.p.m.

Results (1) For cutting tooth enamel and dentine the bur without the embedded coil yielded good results.

(2) For the same operations, use of a bur with the imbedded coil gave excellent results.

(3) In general the higher speeds produced better results.

(4) The saline solution served both for cooling purposes and to improve the anesthetic effects.

Although the description of our invention has been limited primarily to dental drilling, it is apparent that it could apply to other dental operations where a rapidly rotating tool contacts the patients body, such as grinding or polishing. More generally, it is not actually limited to dental operations; it could be used in various modifications wherever a pain-producing, rapidlyrotating, medical tool contacts the patients body. Therefore, while We have described various preferred embodiments of the inven tion, it will be understood that we wish not to be limited by the foregoing description, but solely to the claims granted to us.

What is claimed is:

l. The method of producing electric anesthesia in medical and dental operations which employ pain-producing rotating tools contacting the patients body, comprising the steps of producing a fixed unidirectional magnetic field, positioning said field to bridge the tool-contacting area of the patients body, rotating said tool in said area at a speed generating electric currents in said tool, and passing said currents through said tool to the patient, whereby an anesthetic effect is produced.

2. The method of producing electric anesthesia as in claim 1, further including the step of simultaneously laving the effected area of the patients mouth with an electrolytic solution.

3. The method of producing electric anesthesia in medical and dental operations which employ pain-producing rotating tools contacting the patients body, comprising the steps of producing a fixed unidirectional magnetic field having a strength in the range between 800 and 1,000 gauss, positioning said field to bridge the tool-contacting area of the patients body, rotating said tool in said area with the axis of said tool at an angle to the direction of said field and at a speed generating electric currents in said tool, and passing said currents through said tool to the patient, whereby an anesthetic effect is produced.

4. The method of producing electric anesthesia in medical and dental operations which employ pain-producing rotating tools contacting the patients body, comprising the steps of producing a unidirectional magnetic field, positioning said field to bridge the tool-contacting area of the patients body, rotating said tool in said area at a speed generating electric currents in said tool, passing said currents through said tool to the patient, and adjusting the strength of said magnetic field to a value producing a desired anesthetic effect in the patient.

5. A dental drilling bur for use in relieving pain due to drilling by a form of electric anesthesia generated by rotation of said bur in a magnetic field positioned across the patients tooth, comprising a drill bur shaft, a grinding tip at one end of said shaft, and a coil wound on said shaft with the axis of said coil perpendicular to the axis of said shaft, the turns of said coil extending longitudinally of said shaft and substantially parallel thereto for a major portion of the length of each turn, one end of said coil being connected to said grinding tip.

6. A dental drilling bur for use in relieving pain due to drilling by a form of electric anesthesia generated at the point of drilling by rotation of said bur in a magnetic field positioned across the patients tooth, comprising a drill bur shaft, a grinding tip at one end of said shaft, said shaft having a pair of oppositely disposed longitudinally extending recesses and having a hole extending transversely through said shaft at each end of and interconnecting said recesses, a coil of insulated wire having its turns lying in said recesses and extending through said holes, whereby the axis of said coil is perpendicular to the axis of said shaft, and a major portion of the length of each turn of said coil extends substantially parallel to said shaft.

7. A dental drilling bur for use in relieving pain due to drilling by a form of electric anesthesia generated at the point of drilling by rotation of said bur in a magnetic field positioned across the patients tooth, comprising a drill bur shaft, a grinding tip at one end of said shaft, said shaft having a pair of oppositely disposed longitudinally extending recesses and having a hole extending transversely through said shaft at each end of and interconnecting said recesses, a coil of insulated wire having its turns lying in said recesses and extending through said holes, whereby the axis of said coil is perpendicular to the axis of said shaft, and a major portion of the length of each turn of said coil extends substantially parallel to said shaft, one end of said coil passing through said tip and the other end of said coil being connected to the end of said shaft opposite said tip.

8. A dental drilling 'bur for use in relieving pain due to drilling by a form of electric anesthesia generated at the point of drilling by rotation of said bur in a magnetic field positioned across the patients tooth, comprising a drill bur shaft, a grinding tip at one end of said shaft, said shaft having a pair of oppositely disposed longitudinally extending recesses and having a hole extending transversely through said shaft at each end of and interconnecting said recesses, a coil of insulated Wire having its turns lying in said recesses and extending through said holes, whereby the axis of said coil is perpendicular to the axis of said shaft, and a major portion of the length of each turn of said coil extends substantially parallel to said shaft, one end of said coil passing through a fine bore in the center of said tip and terminating at the edge of said tip so as to provide an exposed point contact.

9. A dental drilling bur for use in relieving pain due to drilling by a form of electric anesthesia generated at the point of drilling by rotation of said bur in a magnetic field positioned across the patients tooth, comprising a drill bur shaft, a grinding tip at one end of said shaft, said shaft having a pair of oppositely disposed longitudinally extending recesses and having a hole extending transversely through said shaft at each end of and interconnecting said recesses, a coil of insulated wire having its turns lying in said recesses and extending through said holes, whereby the axis of said coil is perpendicular to the axis of said shaft, and a major portion of the length of each turn of said coil extends substantially parallel to said shaft, one end of said coil passing through a fine bore in the center of said tip and terminating at the edge of said tip so as to provide an exposed point contact and the other end of said coil being connected to the end of said shaft opposite said tip.

(References 011 following page) References Cited in the file of this patent UNITED STATES PATENTS Horton Mar. 21, 1893 Horton at al Mar. 19, 1895 Simjian Aug. 13, 1957 Bradfild Sept. 17, 1957 Ziegler Aug. 16, 1960 Mitchell J an. 24, 196 1 8 FOREIGN PATENTS 155,294 Germany June 23, 1903 272,416 7 Switzerland Mar. 1, 1951 OTHER REFERENCES Houston and Kennally: Electricity in Electro-Therapanties, pp. 214-220, page 220 relied on, 1896. (Copy in Division 55.) 

1. THE METHOD OF PRODUCING ELECTRIC ANESTHESIA IN MEDICAL AND DENTAL OPERATIONS WHICH EMPLOY PAIN-PRODUCING ROTATING TOOLS CONTACTING THE PATIENT''S BODY, COMPRISING THE STEPS OF PRODUCING A FIXED UNIDIRECTIONAL MAGNETIC FIELD, POSITIONING SAID FIELD TO BRIDGE THE TOOL-CONTACTING 